All you ever wanted to know about satellite dishes but were afraid you've been mislead by manufacturers claims & not so expert exberts. [there are some great experts about both professional & enthusiast, but unfortunately, you tend to need to be a bit of an expert 1st to work out who's an expert & who's not or those trying to be helpful &/or trying to impress people, people deliberately trying to mislead including social media engineering experts- not experienced design / satellite engineers who can look at the manufacturing / design & supply chain of different products from a professional perspective].
We are just interested in who is the best manufacturer/ supplier, dishes that last & from installing & handling & testing so many different manufacturer's products without bias.
THE SIMPLE ANSWER
We have tested many satellite dishes over the years & most [surprisingly]... actually perform very nearly like for like on area if they are well made & in good condition & the LNB or feedhorn is at it's best position for the reflector.
Where they differ is quality, design for fitting/ installing/ adjustment & wind loading, longevity [rust proofing etc.] and one of the biggest - defending from interference/ noise.
It's not actually difficult for most designers / manufacturers nowadays to produce an accurate reflector / press with modern cnc/ cad systems that delivers the signals from the reflector accurately.
There is a lower level of accuracy required for satellite dishes, over a certain point & it is a waste eg compared to say reflecting the much shorter wavelength of light that requires much more accurate polished reflectors/ lenses in the nearest equivalent - optical telescopes].
WHERE SATELLITE DISHES VARY THE MOST [WHAT TO LOOK FOR]
- poor design
- odd design with over the top claims
- cheap materials
- poor rust proofing
- cheap manufacturing
- quality control
- poor shipping & storage
- poor suppliers
Cheap soft mild steel or soft alloy satellite dish faces maybe cheap but these can deform easily in winds, high tensile steel like Triax or HT alloy faces will stay in shape & spring back after very powerful gusts.
Cheaply painted steel satellite dish faces & brackets can rust easily where zinc phosphate treated powder coated steel faces like the Triax steel dish faces, stay rust free for 15-20 years of more,
Poor shallow rim designed faces makes some dishes look bigger but this 'trick' loses face strength as a result & is a good 1st visual indicator of a poor design & probably other poor manufacture elsewhere, a tight angled rim means the designer has at least recognised the importance of the basic engineering strength gained in doing that.
Poor AZEL design makes for more difficult alignment on some satellite dishes more so at the final tighten up stage & gives rise to movement in even light winds on poles & motors, good AZEL design like the Triax dishes give very accurate adjustment [in the hands of an expert- otherwise they can prove difficult for the inexperienced to build & setup] and have the highest grip on a pole of any both in azimuth like snow shoes and it's the elevation design on the Triax AZELs that catch most out & it can be difficult initially to get used to but it's designed like that for reason- once set, it doesn't move & it doesn't crawl after you've fine adjusted it like the Gibertini AZELs do for example & most other satellite dish AZEL bracket designs- but there are tricks to setting the Triax dish's AZELs up far more accurately than possibly any others.
[AZEL is.... the bracket at the back of the dish that holds the dish on the pole/ wall bracket or motor that also allows for azimuth (side to side) & elevation (up & down) adjustment.
Poor shipping can make a big difference too as steel & alloy dish faces can get easily damaged.
Broadcast approved dishes (called type approved & approved by companies like Eutelsat/ Intelsat etc. for use on broadcast) are usually constructed with web like bracing on the rear of the face to keep it true to much higher specifications & take higher wind power.
Regular dishes are usually rated up to 60mph good functionality & up to 100mph survival. Broadcast specification type approved dishes can be spec'd to 50 or 60mph good functionality [for broadcast rx/tx use not dth rx use- using them for dth rx use would be higher] & up to 125mph survival.
Channel Master is probably the best known name wise although it's changed names several times & joined with Andrews some years ago, there's also Prodelin - these are both plastic in construction with an ali' reflector embedded in the plastic face & reinforced with fibreglass & a webbing structure on the rear to support the face integrity.
MEASURING SATELLITE DISHES & COMPARING PERFORMANCE
Many manufacturers use various measuring methods & model numbers that do not relate to the dish size -
For this report data all sizes are for the reflector only and do not include any supporting rim or curved or raised edge to give an honest like for like comparison on area- these are for Width+ Depth /2 or the equivalent area of a round circle & thus PIIr2 will give the surface area.
The older, professional offset dish size measurement is considered the width as the dish & LNB both see a circle with the diameter of the width (true) size at the angle of offset but we consider the area measurement a better overall measure that also factors in the design/ offset angle effect indirectly, the width & height & the beam width characteristics.
Triax (steel press rust proof satellite dishes)
These dishes are very high quality high strength with spring steel pressed faces - zinc phosphate treated & then positively charged powder coated polyester which does give a very good long term rust proofing to the face & can stay 100% rust free for over a decade so far.
Their AZ/ELs are very well designed with a high pole grip clasp design with a galvanized steel substantial curved box shaped support for retaining the dish shape & all nuts & bolts are zinc coated - most stay rust free - rust may creep in if the surface is damage on fitting. The feed arms are pressed aluminium box section & UV plastic fittings. Elevation adjustment is considered difficult to fine tune but once set they are very solid & have several lateral aspects to the pressings. One of the best AZ/EL designs we think but prefer that ....the steel in the AZ/EL to be higher tensile, they add one bolt &/or increase the bolt size for the AZ clamps, change the lnb holder design so lnbs can be swapped without removing, strengthen the feed arm.
Model W+H/2 = to round dia area
TD56 = 50cm x 55cm = 52.5cm
TD64 = 60cm x 65cm = 62.5cm
TD78 = 70cm x 78cm = 74cm
TD88 =85cm x 95cm = 90cm
TD1.1 = 1m x 1.1m = 1.05m
Gibertini
65 = 63cm x 67.5cm = 65.25cm
75 = 72cm x 77cm = 74.5cm
85 = 81.5cm x 87cm = 84.25cm
1m = 94cm x 1.01cm = 97.5cm
1.25m = 1.21m x 1.3m = 1.255m
1.5m = 1.5m x 1.61m = 1.555m
Orbital
80cm = ......cm x ...... cm = 74-76cm
1m = 95cm x 105cm = 100cm
ISS & Technomate
65cm = =
80cm = = 78cm
1m = = 98cm
TELEVES
1m
PENTA
68 = 68cm round dish on area
85 = 85cm round dish on area
Channel Master(Andrews / asc/ Raven/ Skyware Global corp)
90cm = 90cm x 98cm = 94cm
1m = 1m x 1.05 = 1.025m
1.2 m = 1.22m x 1.32m = 1.27m
1.8m = 1.8m x
2.4m = 2.4m x 2.46 = 2.43m
HOW TO MEASURE A DISH ... (TO COMPARE SURFACE AREA v SURFACE AREA).
For this comparison chart dishes are measured by reflective surface area equivalent to a round dish of that diameter only
(or Width + Height / 2) and are for offset design with a single LNB.
Most manufacturers routinely quote different measuring methods or model numbers that do not relate directly to the reflector area so you need to ensure that for any dish tested, the dish size is the reflector area to compare like for like & should not include any supporting rim area. There is another earlier industry standard method of using the offset angle so that the width is the quoted size & the height is deemed the same as viewed in offset- others quote height of reflector or height including the supporting rim or another model number.
This measuring method we have used here demonstrates results manufacturers have achieved with the same surface are.
This does not allow for multiLNB installations where outer LNBs on multi LNB systems require a larger dish to allow for the loss in offset depending how far out of the focus point they are (excluding Toroidal dishes) and to allow for any insertion loss &/or added noise of diseqc 1.0 or 1.1 switches. (see also different measuring methods & different types of satellite dishes).
All figures are based on test sites in the centre of the UK & can still vary due to local interference conditions (town/ city & rural locations & town/ city & rural views), weather conditions and footprint fringe variations in different areas in the UK.
All tests are based on good quality dishes in good condition , sensitive LNBs, cabling & sensitive receivers. These results will not be the same if using cheaper products 'anywhere' in the process or poorly installed.
*most signals reduce the further north in the UK & increase further south in the UK except certain northern Europe beams / Nordic beams such as 1w 5e 23.5e Nordic/ N Europe beams, these N European / Nordic BEAMS can increase as you go north & east of the UK - These can be low or too low on smaller dish sizes - especially 23.5e's.
Other types of satellite dishes
Prime Focus dishes.
Take care in comparing offset dishes with prime focus dishes of the same area as their characteristics are different.
Prime focus satellite dishes offer better local noise & ground noise temperature figures due to the steeper elevation angle & deeper parabola as apposed to the lower elevation & shallower parabola of offset dishes that expose the dish face to more ground & local noise.
The deeper parabola of the prime focus dish gives better ground & local noise & radiation protection to the LNB compared to the more exposed LNB position of the offset dish.
Prime focus dishes are of a deeper parabola & give different beam width characteristics than offset dish of the same surface area/ size- this can be an advantage for satellites wide apart or a disadvantage if it causes more noise to be received from adjacent space & nearby satellites.
The whole surface area of a prime focus dish is what is reflected in to the LNB (except any shadow cast by the LNB & feed support arms) where as the offset dish is deemed to be only as large as the LNB offset angle sees and the greater height measurement is deemed to be reduced to it's width measurement. So a prime focus dish of 1m round is equal to an offset dish of approximately 1m wide by 1.05m high (less LNB / feed arm shadow loss).
The prime focus dish suffers from loss of reflector area due to the signal shadow cast by the LNB & feed support arms compared to the offset dish that does not cast a shadow- usually deemed a quite low loss on dishes over 1.2m
Sky ZONE 1 & 2 dishes & horizontally oval dishes
These are also offset dishes but are wider than their height. This gives a narrower beam width horizontally for their size, giving better separation from other satellites at the sides, but a wider beam depth allowing for better reception of stacked satellites in the same location - a very efficient design for a small dish & used on larger dishes.
The Sky dishes are also paired with feedhorn/ scala ring matched LNBs that are are optimised for use on Sky @ 28.2/5e only. They do require special modification to work as efficiently on all other satellites.
Double reflector dishes
Toroidal Gregorian Cassegrain
Toroidal dishes use a second reflector to allow much wider multi LNB setups without the usual loss at the edges - all LNBs function similarly to being in the centre of the dishes focus. Some of these have been used to cascade 20+ LNBs / diseqc switches & satellite positions.
Gregorian dishes uses a second reflector where the LNB is usually positioned and the LNB then is positioned between the 2nd reflector & the main reflector facing the opposite way- The advantage is deemed a better focus.
Cassegrain dishes are usually prime focus & use a mushroom shaped reflector / collector in the middle of the dish tpo reflect the signal tp an LNB at the back of the dish & claim higher efficiency for their size.
Odd shaped dishes
Penta 68 = to 68cm round on surface area.
Penta 85 = to 85cm round on surface area.
A large number of professionals in the commercial satellite industry consider these dishes as the industry joke dish, many consider the shape & performance claims false. The absence of a dedicated feed horn for these dishes to match the almost square shape (on it's side) is deemed a major failing on their part to give any credibility to it's odd & basic physics rule breaking shape & instead giving rise to increased noise problems being able to enter a standard round LNBf' feedhorn, scalaring & waveguide design from the 4 crescent shaped gaps it produces which, on a basic meter & a spectrum analyser that shows a spectrum of power not signal quality measurements that can appear as a higher signal strength, but instead be energy from noise behind the dish and that the much higher retail costs & low quality of the flimsy dish face unwarranted in practical terms and are instead deemed an amusement & bought only by un-knowledgeable individuals.
We cannot comment too much*** on their performance or cost effectiveness & consider them instead an option for those who see them as an attractive alternative to the traditional oval offset dish with good quality AZ/EL & LNB arm and some other good points. As for the floppiness of the steel version dish face we do agree we have witnessed this & that they can distort in even mild wind but also that they seem to return well to their intended shape & haven't seen a distorted one as yet, although their odd shape does make it difficult to establish whether they are bent or not. The offset angle however, seems to be higher giving an almost prime focus look about the LNB position, this can give the LNB a larger view of the dish than in a lower offset angle and although this normally gives rise to higher noise - in the case of the Penta the basic rules have already been thrown away as it were so it's just as likely to give a gain than more noise.The wider edges (for that size/s) may also give a narrower separation, however the 'points' of the square add to the instability in wind. 
TESTS RESULTS: PENTA 68 v Sky dish. Penta 85 v Triax TD88
In recent extensive tests we found that the Penta 68 was matched or bettered by a Sky dish (zone 2- 64cm) on all the main quality measures of BER/ SNR/ MER/ by a Sky zone 2 dish(64cm) & Triax 64(62.5cm) & 78(74cm) dishes using a surface area like for like test where the larger dish surface area in each case was masked to give exactly the same surface area.
The Sky dish was found to be very efficient indeed per surface area if the offset LNB antennae & oval offset feedhorn design was used correctly on all satellites and the stability of the sky dish proved one of the best designs & build quality per size & offered very high wind speed functionality & very high wind speed survival c. 120klph / 220klph on quality Raven Sky dishes - we think the Penta could become bent inside out at those speeds.
The floppiness of the steel Pentadish face was found quite unstable in quite moderate wind speeds & would distort too easily losing signal compared to calm weather. Worse still, they demonstrated a disturbing resonance/ flapping behaviour in strong side winds that could potentially damage a motor prematurely and not recommended for exposed locations or coastal use. The Penta85 has a supporting bar at the back showing that the designer/ manufacturer have recognised the faults with the unstable shape compared to an oval dish. We also found the overall weight quite excessive for the size & stability of the dish.
SPECTRUM Analysis
When we analysed the signal from a Penta 68 & 64cm Sky zone 2 dish (surface area matched), the Penta 68 appeared to be the greater signal on a professional Rover STC satellite spectrum analyser - particularly at the higher end of KU band- however when we observed both signals in all the quality measures, the lower signals from the Sky dish were 'higher' in quality measures than those from the Penta & also this was reflected in satellite receiver on screen measures. We beleive this to be added power from noise entering the round LNB feedhorn from the crescent shaped gaps caused by the square shape of the Penta. In rural areas we beleive these noise issues would decrease & in city areas become more pronounced.
Taking these findings into account, we still install the Penta dishes for aesthetic reasons over performance but do not agree with the manufacturer's performance claims, dish face stability in strong winds & beleive that the AZ/EL & feed arm is well made except for the elevation pivot & general feed clamp design, we don't have long term durability measures for wind tolerance, paint finish, UV & rusting.
SATELLITE DISH TEST RESULTS:
Gibertini 1m versus Triax 1.1
GIBERTINI 1M [95CM X 105CM] V TRIAX 1.1 [1M X 1.1M]
WINNER = TRIAX 1.1 [OBVIOUSLY] UNLESS THE TRIAX ISN'T FITTED PROFESSIONALLY
Same lnb/ receiver/ location Cheshire England
[Gibertin 1m results 1st Triax 1.1 2nd]
26E BADR 4
DUBAI ONE 75% 78%
KUWAIT 2 TV 74% 77%
BAHRAIN 55 72% 75%
7.3W E7WA NILESAT 104
QATAR TV 71% 75%
8W E8WC
LTV 71% 74%
7e 10e 12.5w 24.5w 3w BROADCAST FEEDS
[various tested]
averages 82% 85%
We have heard some people claiming the Gibertini 1m could actually match & even beat the larger, better made Triax 1.1m dish- including the importer of the Gibertini mistakingly testing one bought at a trade exhibition [which would be perfect] against a poorly installed Triax 1.1- [not a Triax 1.1 we installed].
This simply isn't true in any circumstances of signal level/ snr or interference except overload where the better dish could look lower on basic meters because it's getting such a strong signal the recever gets oveloaded & shows a lower signal quality. This has come out of pure ignorance, giving false information to sell dishes & someone deliberately trying to mislead people because 'purplesat' install Triax 1.1s with scant regard for the truth & people's trust making going on the internet to try to gain information an impossible mix of genuine & fake advice.
We also think it is in part caused by the fact that many people find the Triax AZEL difficult to build & install & the Gibertini 1m uses a very basic, simple to understand AZEL & even uses simple wing nuts, where as the Triax uses a far more advanced, better engineered AZEL that many don't understand but at the end of the day, they grip poles/ brackets & satellite motors better than any other make of dish & for the material they use & why the Triax dishes are the biggest selling dishes in the UK & most of Europe & why their design has been copied so much except for the elevation clasp design.
Basically, if both dishes are installed professionally & to the same level [& honestly], the Triax 1.1 will always beat the Gibertini 1m by about the same margin you'd expect for the greater area/ size. These measurements need to be on weak EIRP satellite beams into the test location [in this case the UK from typically the Middle East satellites like Nilesat/ Arabsat's BADR satellites etc..] & also using outside broadcast feeds which present a slightly different issue with their typically stronger signal levels but more delicate transmissions with more use of DVB-S2/8PSK, lower than acceptable for dth error correction, lower symbol rates & narrower bandwidth transponder leasing eg 4-6MHz rather than c. 70MHz for dth like bbc / sky etc,,..
So the next time you see someone saying the Gibertini 1m can match or even beat a Triax 1.1- remember, only someone who has little knowledge would go round saying that or someone trying to deliberately mislead, there's no hidden magic- a bigger dish will beat a smaller dish if the face is equally accurate & in good condition. So ask them to prove it. & if you own a Gibertini 1m, don't worry, they are an OK dish face for their size, they just wont alter the laws of physics & we are not happy with the design, esprcially of the big / heavy chunky AZEL, the elevation adjustment & how it creeps as you try to really tighten it up, the inferior pole clamp design, the wing nuts which we throw away & replace with nuts & washers, the amnount it all sticks out, especially mountred on a diseqc motor & even worse on their polarmount which we have to modify to make worl well- otherwise it;s too unstable. The feed arm design which can work loose. The Gibertini 1m satellite dish was far worse as the AZEL design stuck out far more until our main engineer critisized this odd design ... and the went and altered it to a tighter design. We think the designer/s at Gibertini have or had little understanding of the importance of limiting leverage & weight by keeping AZELs & polarmlounts tight in & light.
Bigger Dishes Usually Get Better Signals.
OFFSET DISHES
1m wide x 1.05m high versus 1m wide x 1.1m high
Several people insist that because the offset satellite dish design is intended for the lnb to see the vertical oval shaped offset dish as a round circle of signal of the diameter of the width, that such a difference as the height being taller cannot possibly make any difference providing the feed is not casting any shadow. What they fail to allow for is that we do not work on signal power alone but signal versus noise/ interference & the typical offset dish is deemed to only be 70% efficient with the true p[icture of signal reflection being much more wooley, especially towards the edges & much cleaner towards the middle & therefore there is up to 30% to be gained.
The extra area of the taller 1m wide design can deliver a better signal [overall] because it reflects more of the better area & effectively, the larger area basically offers more sheilding from noise at the edges.
The Fibo/ Gregorian design dishes demonstrate this in a different way [improving snr not signal aquisition] , the secondary reflector means the overall area is larger & is recognised by companies like Channel Master as a contributing factor in better signal to noise & why you'll see the Gregorian design used in broadcast industry. What it does is reduce noise & increase signal from the available signal eating into the lost 30% by the facty that oit sheilds the feed better from noise. Changing elevation by flipping offset angles can do a similar thing if you examine noise over elevation figures of say 10 degrees / 20 degrees / 30 degrees - the higher the elevation, the less noise- mostly ground noise from the Earth but increasingly also man made sources.
SATELLITE DISH OVERALL RECEPTION/ SNR
PERFORMANCE
MAIN LIST.
No# AREA RATING_QUALITY _DESIGN SNR _NAME _________________________________
- 39 ___35_____C __CAMPING DISHES 39CM
- 42 ___45_____A __SKY ZONE 1 42CM
- 45 ___48_____A __SKY ZONE 1 45CM RAVEN CHANNEL MASTER [YES]
- 50 ___53_____A___SKY ZONE 1 50CM RAVEN/ INVACOM
- 50 ___54_____A___SKY ZONE 1 50CM TRIAX
- 56 ___56_____A___TRIAX 56CM
- 60 ___60_____B___60CM [55CM X 65CM] REGULAR 60CM OFFSET
- 64 ___64_____A___TRIAX 64CM
- 64 ___68_____A___SKY ZONE 2 64CM RAVEN INVACOM
- 68 ___66_____A___FRACARRO PENTA 68
- 64 ___69_____A___SKY ZONE 2 TRIAX
- 74 ___74_____A___TRIAX TD78 ORBITAL 80 ISS 80
- 80 ___80_____B___80CM [75CM X 85CM]
- 85 ___82 ____A___ PENTA 85
- 85 ___85_____B___ISS 80 [80CM WIDE VERSIONS]
- 85 ___85_____ A___LENSON HEATH 80
- 90 ___90_____AA__TRIAX TD88 FUNKE 90 LENSON HEATH 90
- 90 __ 95 _____ AA__FIBO 90
- 98 ___98_____ A___TECHNOMATE 98
- 100 __100 ____B___ISS 1M (1M WIDE VERSIONS)
- 100 __100_____B___ORBITAL 1M
- 100 __100_____A___GIBERTINI 1M
- 105 __105_____AA__TRIAX TD110
- 106 __106_____B___MAX DIGITAL 1.1
- 115 __115_____B___SAC 1.2M STEEL
- 115 __115 ____A ___FRACARRO 1.2M (1.2 X 1.1)
- 125 __125_____A___GIBERTINI / HIRSCHMANN 1.25 (1.2 X 1.3)
- 125 __125_____AAA_ CHANNEL MASTER ASC SIGNAL RAVEN SKYWARE
- 125 __ 125 ____AAA_ ANDREWS
- 125 __ 125 ___ AAA__PRODELIN 1.2
- 127__127____ A____FRACARRO 1.25
- 125 __130 ____AA___FIBO 1.2
- 140 __130_____B____FAMAVAL 1.4M PF
- 150 __150_____A____GIBERTINI / HIRSCHMANN FRACARRO 1.5M
- 180 __168_____B____FAMAVAL 1.8M PF
- 183 __183_____AAA__CHANNEL MASTER ANDREWS ASC SIGNAL RAVEN SKYWARE
- 183 __183 ____ AAA__PRODELIN 1.8M
- 230 __210_____B____FAMAVAL 2.3M PF
- 243 __243_____AAA__CHANNEL MASTER ANDREWS ASC SIGNAL RAVEN SKYWARE PRODELIN 2.4M
- 250 __240_____AAA__CHANNEL MASTER 2.5M PF
- 310 __300_____C____FAMAVAL 3.1M PF
- 370 __360_____A____PATRIOT 3.7M
- 360 __350_____AAA__PRODELIN 3.6M
- 400 __390_____AAA__PRODELIN 4M
- 470 __460_____AAA__PRODELIN 4.7M
Contact purplesat.com for any queries regarding satellite installations.
TEL: 07931 846757
International TEL: 00 44 1625 615379